TNF and infection: In the cardiac tissue of infected STAT3 KO mice, the mRNA expression of the proinflammatory cytokines IL-1β (8.95 ± 3.00 fold, P = 0.0111), IL-6 (17.19 ± 5.39 fold, P = 0.0140), and TNF-α (4.39 ± 0.96, P = 0.0055) was significantly increased 10 days after infection compared to the expression levels in untreated STAT3 KO mice.